Journal of Exercise & Organ Cross Talk

Abstract The study aimed to compare the acute effects of low resistance exercises with partial and complete blood flow restriction (BFR) and heavy resistance exercise on growth hormone (GH), myostatin, testosterone, and cortisol in competitive wrestlers. Forty elite wrestlers were randomly divided into four groups (n=10); low resistance training with complete BFR (LRT+CBFR), low resistance training with partial BFR (LRT+PBFR), low resistance training (LRT), and heavy resistance training (HRT). Blood samples were collected before and after the intervention, and a specific ELISA kit measured variables. Analysis of covariance and paired t-test was performed to analyze the data. There were no significant differences in the variables between the four interventions. Intra-group results showed a significant decrease in myostatin levels in the HRT group (p=0.02), and a significant increase in GH in the LRT+CBFR (p=0.02) and LRT+PBFR (p=0.03), testosterone in the HRT group (p=0.04) and cortisol in the three groups LRT+CBFR (p=0.02), LRT+PBFR (p=0.01) and HRT (p=0.04). Despite the similarity of the changes in the four interventions, due to the percentage of changes, it seems that low resistance training with BFR could produce similar anabolic effects to high-intensity resistance training.

Abstract The aim of our study was to examine the effect of 12 weeks of moderate-intensity aerobic exercise on bone mineral density (BMD), lymphocyte alkaline phosphatase (ALP) mRNA expression, and biochemical markers of bone turnover in postmenopausal women (PMWs). Twenty-four healthy sedentary PMWs aged 45-70 years were randomly assigned to exercise (EX, n=12) and control (C, n=12) groups. The EX group performed walking/jogging (50-60min/day, 3days/week at 65%-70% HRmax reserve) for 12-week while the C group participated in no intervention and continued their normal lifestyle. The BMD and lymphocyte ALP mRNA were determined by DXA and qRT-PCR, respectively. After 12 weeks, the increase in the lymphocyte ALP mRNA expression and its serum (P=0.008 and P=0.001), PTH (P=0.001), Vit-D (P=0.002), and VO2max (P=0.001) were significantly higher in the EX group compared to the C group, whereas body fat was significantly decreased (P=0.028). Our study indicates that 12 weeks of moderate-intensity aerobic exercise intervention improves bone turnover by increasing the ALP mRNA expression, serum levels of PTH, ALP, and Vit-D which can lead to the prevention of aging-induced osteopenia among PMWs.

Abstract The purpose of this study was to compare the effect of two methods of resistance training TRX and traditional resistance on the response of some indicators of muscle damage in soccer players. The present study was a semi-experimental; therefore, 36 participants with mean age of 19/36±1/4 were voluntarily selected and assigned to two groups of TRX and traditional resistance training. The training program for both groups consisted of several joint movements, these movements in 2 sets, with 8 repetitions in to isometric form, and the duration of muscle tension in each movement was 20 seconds. Both groups were evaluated by biochemical, physical and anthropometric measurements in two stages of pre-test and post-test. Data analysis was done using independent sample t-test and paired sample t-test with the significant level of 0.05 (p≤0.05). Serum creatine kinase levels showed a significant increase in traditional resistance training group 54.01% (p=0.001) and in the TRX training group 58.19% (p=0.003). Serum lactate dehydrogenase levels increased significantly as the result of traditional resistance training (p=0.033) while Aspartate aminotransferase did not show any significant changes from pre-test to post-test in the experimental groups. Moreover, the results of the present study showed that there was no significant difference in the changes observed in the indices of muscle damage between a traditional training and TRX training. Therefore, performing TRX or traditional training is not improving muscle injury during training.

Abstract It has been proven that strenuous endurance training increases oxidative stress in body. This study investigated the effects of curcumin supplementation and light resistance training during 8 weeks of endurance training on muscle and serum antioxidant capacity and lipid peroxidation of male wistar rats. 44 male Wistar rats (weight: 254.31±17.72 g and age: 8 weeks) were randomly divided to 6 groups; Control (n=6, sham), Curcumin (n=6), Endurance (n=8), Endurance-curcumin (n=8), Endurance-Resistance (n=8), and Endurance-curcumin-resistance (n=8). Endurance training performed on rodent treadmill for 8 weeks and 5 sessions a week. The speed and duration of running were 10 m/min and 30 min at first week. The intensity and duration reached to the 35 m/min and 70 min up to the last week. Resistance training (8 weeks, 2 sessions / week) performed on vertical ladder (with 30-70% BW). The animals received curcumin supplement by sub peritoneal injection (8 weeks, 3 sessions / week, 30 mg/kg.Bw). Superoxide dismutase (SOD) enzyme activity was measured by Elisa kit and Malondialdehyde (MDA) was measured by the thiobarbituric acid reactive substances (TBARS).  The results of this study showed that strenuous endurance training (p<0.05) reduces the serum levels of SOD significantly, and caused a significant increase in the lipid peroxidation (MDA in muscle and serum). Curcumin supplementation and light resistance training could increase antioxidant enzymes activity (SOD) and decrease the MDA levels. The prolonged strenuous endurance training can induce oxidative stress and curcumin supplementation along with light resistance training could restore antioxidant enzymes activity and decrease the MDA levels.

Abstract The main purpose of this study was to investigate the effect of primary swimming on the hormonal anabolic-catabolic balance and serum leptin in obese children and adolescents. Sixty obese subjects (children and adolescents) were randomly assigned to one of four groups: 1) Primary swimming training (children); 2) control (children); 3) Primary swimming training (adolescents); and 4) control (adolescents) groups. Our experimental subjects performed a primary swimming training for 8 weeks, 3 sessions per week and 60 minutes per session. Before and after training period, blood samples, anthropometric and body composition measurements were taken in fasting state from all subjects. The findings showed that the primary swimming training prevents significant increase of serum leptin and insulin hormone in adolescents. Furthermore, primary swimming training caused a significant decrease in body fat percent, body fat mass and body mass index, a significant increase of VO_2max in children and adolescents, a significant decrease in cortisol hormone as well as a significant increase in fat free mass in adolescents (p<0.05). There was a positive and significant correlation between levels of leptin changes and body fat percent and fat mass after primary swimming training (p<0.05). In addition, there was a negative and significant correlation between levels of leptin hormone changes and fat free mass after primary swimming training (p<0.05). Therefore, it can be concluded that eight weeks of primary swimming training improves serum leptin and some of the anthropometric, hormonal and metabolic parameters.

Abstract Dear Editor-in-Chief
During pregnancy, regular physical activity contributes to the health of the mother and fetus, which is due to the effect of exercise on the mother's physiological regulation, growth, and optimal function of the fetal placenta. But the mechanism of this effect is unknown. Recently, studies have shown that exercise can connect multiple tissues through the tissue secretomes. Muscle tissue secreting myokine can affect distant tissues such as the liver, adipose tissue, brain, skin, and even the placenta. However, other tissues can also affect muscle tissue. The human placenta as multifunctional organ releases large amounts of hormones, cytokines, placental proteins, non-coding RNAs, as well as extracellular vesicles into the mother's bloodstream (Adam et al., 2017). Exosomes are nanometer-sized extracellular vesicles produced by the endosomal pathway and packed with tissue-specific molecules. Because these nanoparticles can selectively target specific cells and transmit their contents to receptor cells, they form an integral pathway from cell-to-cell communication (Valadi et al., 2007). For example, exosomes secreted from the placenta reduce insulin sensitivity in muscle tissue and improve glucose metabolism in skeletal muscles during pregnancy (Nair et al., 2018). Since exercise itself is effective in improving insulin sensitivity, especially during pregnancy, it seems that one of the mechanisms involved could be the regulation of placental exosome secretion and its effect on muscle tissue, which has not been studied so far.
Evidence suggests that skeletal muscle during exercise by secreting endocrine factors such as myokines affect liver, adipose tissue, and placenta during pregnancy. Moreover, myokines can improve glucose and fat metabolism in mother’s body (Laurens, Bergouignan, & Moro, 2020).  So far, more than 600 myokines have been identified, the most important of which is irisin. This factor is secreted from muscle tissue and can affect the metabolism of other tissues, including white adipose tissue. It has also been reported that the level of this myokine can increase during pregnancy. The vital involvement of irisin in various key metabolic pathways increases attention to considering the effects of this myokine during pregnancy. Maternal circulating levels of irisin were measured in the range of 5-50 nM (Seven et al., 2019). In pregnant women during normal pregnancy, this factor is significantly higher than irisin levels in non-pregnant women. The potential role of circulation irisin on placenta is currently unknown. Since muscle contraction and exercise cause a significant increase in irisin expression (Sousa, Improta-Caria, & Souza, 2021), it seems that exercise during pregnancy with an increase in irisin also affects the placenta, which needs further investigation.
Recently, it was observed that maternal exercise stimulates the expression of myokine and adipokine apelin in addition to adipose tissue and skeletal muscle in human placenta. The new "exerkine" apelin appears to play a regulatory role in response to exercise during pregnancy in metabolic health (such as energy metabolism, fluid homeostasis, blood pressure, etc.) and fetal muscle development (Son et al., 2020). Furthermore, Bhattacharjee et al. in a current human study showed that regularly physically active women during pregnancy have a significantly increased placental expression of the myokine vascular endothelial growth factor (VEGF) and its VEGF receptor-1 compared to inactive women (Bhattacharjee et al., 2021). Further research is needed to assess the cross-talk between apelin and VEGF and the placenta in more details.
Fibroblast growth factor 21 (FGF21) is also a key regulator of endocrine and paracrine glucose and lipid metabolism, which is secreted from muscle tissue and can affect other tissues, including the placenta. FGF21 appears to affect the placenta through FGFRs and co-receptor β-klotho (Sun, Sherrier, & Li, 2021). Therefore, according to the evidence, it seems that the study of cross-talk subtypes of the endocrine family of FGFs (FGF19, FGF21, FGF23) and especially FGF21 with klotho protein along with the intervention of physical activity is a new topic to identify the mechanism. The effects of exercise on the human placenta need to be examined more closely (Bhattacharjee, Mohammad, & Adamo, 2021).
 

Abstract Dear Editor-in-Chief
New approaches to endocrinology have confirmed that every cell secretes hormones. These secreted substances are called cytokines. However, they are also named based on their origin. For example, the secretions of adipose and muscle tissue cells are called adipokines and myokines, respectively (Chait & den Hartigh, 2020).
The endocrine function of adipose tissue has been determined in some studies. It secretes substances called adipokines. Released adipokines (such as leptin, adiponectin, visfatin, resistin, omentin) act as autocrine/paracrine and endocrine (Landecho et al., 2019).
 Adipokines play an essential role in regulating glucose and lipid metabolism, energy homeostasis, nutritional behavior, insulin sensitivity, inflammation, the immune system, adipose tissue production, vascular function, coagulation, and other bodily functions (Chait & den Hartigh, 2020). Leptin, for example, regulates body fat mass and obesity (when it increases in the bloodstream) through appetite and satiety receptors (in the hypothalamus). Unlike leptin, adiponectin reduces body fat mass and regulates glucose and lipid homeostasis. The resistin can be thought of as a link between obesity, diabetes, and insulin resistance. The visfatin plays an essential role in inflammatory and infectious diseases through pro-inflammatory and anti-apoptotic ability. Omentin significantly reduces the acute phase protein in endothelial cells and can be considered an anti-inflammatory adipokine (Landecho et al., 2019). In general, adipokines act as a mediator in regulating the function of tissues and other organs such as the liver, skeletal muscle, pancreas, and cardiovascular system. Adipose tissue dysfunction plays a significant role in insulin resistance, type 2 diabetes, cardiovascular disease, and metabolic disease (Balistreri, Caruso, & Candore, 2010).
Exercise promotes adaptation to skeletal muscle, adipose tissue and consequently prevents metabolic disorders. Physical activity causes these beneficial effects by altering myokines (skeletal muscle secretions) and adipokines. Adipokines and myokines play a role in facilitating tissue-to-tissue communication (tissue crosstalk) and work together to improve health. Studies show that skeletal muscle releasing myokines during a contraction may influence adipokines (Leal, Lopes, & Batista, 2018). Moreover, Shirvani et al. showed a significant positive correlation between plasma levels of irisin with the nesfatin-1 and a significant negative correlation with resistin. Therefore, physical activity could create metabolic crosstalk between skeletal muscle and adipose tissue (Shirvani & Rahmati-Ahmadabad, 2019). Doing crosstalk research by researchers is crucial to better understand the health-related molecular mechanisms (created by exercise).

Abstract Dear Editor-in-Chief
Different types of exercise training with increasing muscle contraction can stimulate muscle secretome called myokines. Myokines are the main mediators of maintaining muscle structure and function in manner of autocrine and paracrine. These myokines can both affect distant tissues and have positive effects on muscle tissue itself (Chen, Wang, You, & Shan, 2021). In various diseases leading to muscle wasting, it seems that exercise and increased contraction can reduce the rate of muscle wasting and muscle atrophy by regulating myokines. Myostatin is a myokine that negatively regulates skeletal muscle development. In animal models, myostatin degradation has been shown to increase muscle mass and inhibit myostatin signals which can control the loss of muscle mass due to cancer cachexia (X. Zhou et al., 2010). Zhou et al. (2021) showed that exercise training (strength or balance in combination with endurance training) seems to be effective in preventing sarcopenia and maintaining muscle mass in non-dialysis-dependent patients with chronic kidney disease (CKD) with inhibition of myostatin signaling (Y. Zhou, Hellberg, Hellmark, Höglund, & Clyne, 2021).
Apelin is another myokine that decreases in age-dependent manner (Vinel et al., 2018). Apelin signaling in aging helps to increase muscle function by stimulating mitochondrial biogenesis and anti-inflammatory pathways in myofibers and improving regenerative capacity by targeting muscle stem cells (Vinel et al., 2018). It has been shown that exercise can positively regulate the Apelin and improve muscle growth. Apelin, an exerkine, is elevated due to maternal exercise, and maternal apelin administration mirrors the effect of maternal exercise on mitochondrial biogenesis in fetal muscle (Son et al., 2020). In other words, Apelin inhibits skeletal muscle dysfunction.
Leukemia inhibitory factor (LIF) is primarily expressed at low levels in type 1 muscle fibers. LIF has been shown to affect the growth and regeneration of skeletal muscle. For example, the expression of LIF protein in rat plantaris muscle is increased by mechanical load (Sakuma et al., 1998). Furthermore, LIF stimulates the hypertrophic response to increased load in the animal model, and in this respect LIF has been shown to be an important factor in skeletal muscle hypertrophy. In addition, LIF mRNA increases in human skeletal muscle following muscle damage leading to better repair. Therefore, this factor secreted by skeletal muscle can increase in various injuries and diseases with exercise and controls muscle wasting. Irisin is one of the most important muscle myokines that is secreted from muscle tissue through exercise and has auto and paracrine effects. It was shown that the injection of irisin induced muscle hypertrophy, improved muscle strength and reduced necrosis and development of connective tissue in a murine model (Reza et al., 2017). Therefore, increasing this factor with exercise can counteract cachexia and atrophy.
Musclin is an exercise-responsive myokine associated with plasma atrial NP (ANP) and cyclic guanosine monophosphate (cGMP) and the expression of the peroxisome proliferator-activated receptor γ coactivator 1-α (PGC1-α) expression in skeletal muscle after exercise training (Subbotina et al., 2015). Musclin helps increase exercise capacity by increasing mitochondrial biogenesis in mice (Subbotina et al., 2015). In addition to its role in exercise, Musclin reduces muscle tissue damage during the development of cachexia-induced tumors and has beneficial effects on cancer patients at risk for cachexia (Re Cecconi et al., 2019). C - X - C motif chemokine ligand 12 (CXCL12) is another type of myokine that is involved in the growth of skeletal muscle. CXCL12 helps proliferate myogenic and angiogenic somite progenitor cells and controls myotoma formation (Abduelmula et al., 2016). Moreover, it has been shown that the concentration of plasma CXCL12 is enhanced in response to training on a bicycle ergometer (Wang, Lee, Lien, & Weng, 2014). Overall, muscle - muscle crosstalk with several myokines mediates the beneficial effects of exercise training, including regulating muscle growth, preventing muscle loss, and increasing muscle function and regeneration, and these factors can decrease muscle wasting diseases.